Recently, in German Offenlegungsschrift No. 2,165,651 a group of isoindole-1,3-diones which are useful as herbicides was disclosed. The general formula for the isoindole-1,3-diones disclosed in the Offenlegungsschrift is as follows: ##STR2## wherein R may be an aryl, aralkyl or benzyl substituent optionally substituted with 1 to 5 halogen atoms or a hydroxy, nitro, cyano, thiocyanato, carboxy, alkyl or halogenated alkyl, alkoxy, lower alkylthio or phenyl group. R may also be optionally substituted with a group having the configuration --O--CH.sub.2 A where A is phenyl or a naphthyl group. The phenyl group may contain one or more halogen atoms, nitro groups, lower alkyl groups or lower alkoxy groups.
Typical of the compounds disclosed in the Offenlegungsschrift is the compound of Structure 1: ##STR3##
Although the compounds disclosed within the Offenlegungsschrift are active herbicides, the need still exists for even better herbicides. Weeds are very damaging to important crops such as rice and wheat and they decrease crop yield. In the current world situation, wherein food shortages are acute, it is most important to harvest the maximum possible yields of crops such as rice or wheat. Thus, a need exists for a particularly effective herbicide which will destroy as many weeds as possible without causing significant damage to desired crops, e.g., rice or wheat.
According to the instant invention, compounds have been discovered which are highly active herbicides and yet cause minimal damage to certain desired crops, e.g., rice and wheat, and especially the major world food crop, rice.
The preparation and fungicidal utility of the 2-(4-chlorophenyl)-1,2,4,5,6,7-hexahydroindazol-3(3H)-one is disclosed in Takeda Chem. Ind. Paper, Chem. Abs., 67, 11542h (1967). ##STR4##
2-Aryl-4,5,6,7-tetrahydro-1-alkyl-1H-indazol-3(2H)-ones are claimed as antipyretics in Ger. 668.628 [assigned to P. Bierdorf & Co. AG, Chem. Abs., 33, 5131.sup.2 (1939)] and U.S. Pat. No. 2,104,348 [assigned to E. R. Squibb, Co., Chem. Abs., 32, 1869.sup.1 (1938)]. ##STR5## 0041
German Offenlegungsschrift No. 2,409,753 discloses herbicides having the general formula ##STR6## in which
R.sup.1 is hydrogen, an alkyl, cycloalkyl or aralkyl radical, a phenyl group which may be substituted or an acyl radical having the formula --CO--R.sup.6 or ##STR7##
R.sup.6 is hydrogen, an alkyl radical which may be substituted, an alkoxy or phenoxy radical or a phenyl radical and
R.sup.7 and R.sup.8 are the same or different and can be hydrogen, alkyl, phenyl which may be substituted or alkinyl,
R.sup.2 is an alkyl radical which may be substituted, a cycloalkyl radical or a phenyl radical which may be substituted or a heterocyclic radical with O, N or S atoms in the ring,
R.sup.3 is hydrogen, chlorine, bromine or a low-molecular-weight alkyl radical,
R.sup.4 is the radical --S--R.sup.5, --SO--R.sup.5 or --SO.sub.2 --R.sup.5 and
R.sup.5 is an alkyl radical, cycloalkyl radical, aralkyl radical or a phenyl group which may be substituted or a heterocyclic radical with O, N or S in the ring.
An intermediate for preparing these herbicides by reaction with a mercaptan having the general formula R.sub.5 SH is ##STR8## where R.sup.1, R.sup.2, R.sup.3 and R.sup.5 have the previously given meanings and Hal represents chlorine, bromine or iodine.
1-Phenyl-3,4-trimethylenepyrazolone is disclosed in U.S. Pat. No. 1,685,407 (1928) with utility as an intermediate for making dyes and medicinal compounds. C. Mannich in Arch. Pharm. 267, 699-702 (1929) and in Brit. 260,577 describes the preparation of 1-phenyl-3,4-trimethylenepyrazolones. ##STR9##
R. P. Willliams et al. in J. Med. Chem. 13, 773 (1970) reports the preparation and evaluation as anti-inflammatory agents compounds of the following type: ##STR10## X = H, Br, F.